Chinese ammo made for the Kingdom of Saudi Arabia
The ammo was made at 791 in ChongQing according to Canada Ammo in 2011.
the head stamp will be "CBCC 7.62x39 05" and boxes inside look like this, Made in 2005, Could be non corrosive, Could not. But there is so little information on this ammo the only real way to know would be a nail test.
The crate in the photo also shows the consignee as Canada Ammo. Some members here may remember buying some. Was most likely before my time.
I found one reddit post from 9 years ago "My crates of surplus copper washed non-corrosive Chinese-made x39 marked "Kingdom of Saudi Arabia, Ministry of the Interior, Riyadh" beg to differ."